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000
FXUS64 KBRO 041445 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
845 AM CST WED DEC 4 2013

.DISCUSSION...UPDATED FOR LATEST MARINE DISCUSSION BELOW.

&&

.MARINE...EXTENDED MARINE DENSE FOG ADVISORY UNTIL 10 AM BASED ON
WEB CAM OBS.

&&

.PREV DISCUSSION... /ISSUED 532 AM CST WED DEC 4 2013/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...A MIX OF VERY LOW CLOUDS AND LIGHT FOG WILL CONTINUE TO
AFFECTED HRL AND MFE AERODROMES THROUGH MID MORNING. VFR
CONDITIONS CURRENTLY AT BRO BUT WILL MENTION TEMPO THROUGH 13Z FOR
BRIEF LOW CEILINGS/VISIBILITIES. SUNSHINE AND INCREASING WINDS
WILL DISSIPATE THE FOG BY MID TO LATE MORNING. VFR CONDITIONS WILL
DEVELOP LATER THIS MORNING THROUGH THIS EVENING. ANOTHER ROUND OF
LOW CEILINGS AND FOG...POSSIBLY DENSE... EXPECTED LATER TONIGHT.
LIGHT TO MODERATE SOUTH TO SOUTHEAST WINDS WILL PERSIST THROUGH
THE PERIOD.

PREV DISCUSSION... /ISSUED 406 AM CST WED DEC 4 2013/

SHORT TERM.../NOW THROUGH THURSDAY/...THE MAIN ISSUE THROUGH THE
FORECAST PERIOD WILL BE FOG. LIGHT SURFACE WINDS IN COMBINATION WITH
MOSTLY CLEAR SKIES AND INCREASING MOISTURE HAS ALLOWED AREAS OF FOG
AND LOW CLOUDS TO DEVELOP ACROSS THE AREA THIS MORNING. STRONGER
SOUTH WINDS HAVE KEPT VISIBILITIES FROM DROPPING TO DENSE FOG LEVELS
THUS WILL HOLD OFF ON ISSUING A DENSE FOG ADVISORY AT THIS TIME. THE
FOG WILL LAST THROUGH MID MORNING AND WILL BEGIN TO LIFT AND MIX OUT
AS DAYTIME HEATING INCREASES IN THE MORNING.

ZONAL FLOW ALOFT WILL BACK TO SOUTHWEST BY LATER TONIGHT AS THE
TROUGH DEEPENS OVER THE NORTHERN ROCKIES. CIRRUS CLOUDS EXPECTED TO
STREAM OVERHEAD THROUGH THURSDAY DUE TO THE WEST TO SOUTHWEST FLOW
ALOFT. SURFACE HIGH PRESSURE OVER THE GULF OF MEXICO WILL MAINTAIN
SOUTHEAST TO SOUTH WINDS ACROSS REGION THROUGH THURSDAY. VERY WARM
TEMPERATURES AND HUMID CONDITIONS EXPECTED ACROSS THE AREA THIS
AFTERNOON AND AGAIN ON THURSDAY AFTERNOON AS DRY SOUTHWESTERLY FLOW
AT 850 MB WILL ALLOW HIGH TEMPERATURES TO CLIMB INTO THE MID TO
UPPER 80S AT MANY LOCATIONS EACH DAY. OVERNIGHT LOW TEMPERATURES
TONIGHT WILL BE IN THE 60S TO AROUND 70 NEAR THE COAST.

MODEL POINT SOUNDINGS AND SREF LOW CLOUD/LOW VISIBILITY PRODUCTS
INDICATE A BETTER CHANCES OF WIDESPREAD FOG ACROSS THE AREA...SOME
DENSE...LATER TONIGHT THROUGH MID MORNING ON THURSDAY.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...THE NORTH AMERICA
MID TO UPPER LEVEL CONTINUES TO TRANSITION INTO A CLASSIC POLAR
AIR OUTBREAK. DETERMINISTIC AND ENSEMBLE MEMBERS ARE WITHIN FAIRLY
GOOD CONSENSUS WITH THE DEVELOPMENT OF THIS COLD PATTERN. UPPER
RIDGE TO BUILD ALONG THE WEST COAST INTO ALASKA WITH A LARGE
POSITIVELY TILTED TROUGH SETTING UP SHOP OVER THE CONUS. A VERY
HIGHLY AMPLIFIED NORTH FLOW DEVELOPS FROM CANADIAN YUKON TO THE
SOUTHERN ROCKIES WHICH IS KEY TO SURGE ARCTIC AIR WELL SOUTH. THIS
SHOULD KEEP DEEP SOUTH TEXAS TEMPERATURES WELL BELOW NORMAL
THROUGH THE ENTIRE EXTENDED PERIOD. MAIN CHANGES TO THE FORECAST
WERE TO LOWER TEMPERATURES DURING THE LATTER HALF OF THE PERIOD
WITH ADDITIONAL ADJUSTMENTS LIKELY AS THE TROUGH BECOMES
ESTABLISHED.

FIRST OF TWO ARCTIC FRONTS TO SURGE THROUGH THE REGION FRIDAY
MORNING WITH TEMPERATURES FALLING RAPIDLY BEHIND THE FRONT. STRONG
NORTH WINDS TO DEVELOP WITH THE FRONTAL PASSAGE WITH POSSIBLE
THUNDERSTORMS. SOME INSTABILITY AND LIFT IS INDICATED ALONG AND
JUST BEHIND THE FRONT TO KEEP THE CHANCE OF THUNDER IN THE
FORECAST. THE SURFACE INVERSION QUICKLY DEVELOPS WITH CONVECTION
CHANGING OVER TO A MORE STRATIFORM RAIN THROUGH THE AFTERNOON.
TEMPERATURES TO CONTINUE FALLING THROUGH THE DAY WITH ALL AREAS
LIKELY TO BE IN THE 40S...WITH EXCEPTION TO THE COASTAL AREAS...BY
MID TO LATE AFTERNOON.

AS THE UPPER TROUGH ESTABLISHES ITSELF TO OUR WEST A STRONG
OVERRUNNING PATTERN DEVELOPS OVER SOUTH TEXAS FOR SATURDAY. THERE
IS A SHORT WINDOW FOR SOME RAIN SLEET MIX EARLY SATURDAY ACROSS
THE NORTHERN RANCHLANDS WITH A SHALLOW SATURATED LAYER FALLING
BELOW FREEZING. NO ACCUMULATIONS ARE EXPECTED AND NO MENTION IN
THE GRIDS/FORECAST AT THIS TIME. WILL HAVE TO WAIT FOR THE COLD
AIR TO BECOME ESTABLISHED AND SEE WHERE A COASTAL TROUGH/LOW SETS
UP BEFORE MENTIONING ANY WINTER ADVISORY CONDITIONS. AS THE SURFACE
INVERSION STRENGTHENS CLOUDS TO THICKEN AND DRIZZLE TO
DEVELOP. STRONG NORTH WINDS AND PLENTY OF COLD AIR SURGING SOUTH
TO KEEP TEMPERATURES IN THE 40S WITH SOME NORTHERN LOCATIONS
STRUGGLING TO REACH 40. VERY COLD SATURDAY NIGHT WITH SOME SLIGHT
RELIEF FROM COLD TEMPERATURES SUNDAY IF CLOUDS THIN WEST TO EAST
AND A COASTAL TROUGH/LOW MOVES FARTHER EAST IN ADVANCE OF THE NEXT
COLD FRONT. ANOTHER SHOT OF ARCTIC AIR MOVES THROUGH MONDAY WITH
BOTH THE ECMWF AND GFS IN GOOD AGREEMENT. ECMWF IS HOWEVER COLDER
AS STRONGER SURFACE RIDGE IS INDICATED TO BE FARTHER SOUTH IN
TEXAS. TRENDED WITH THE COLDER EUROPEAN GUIDANCE. RAIN CHANCES TO
LOOK TO BE LOW WITH MOISTURE VALUES CONTINUE TO DECREASE AS NORTH
WINDS PREVAIL AND LOWER DEW POINTS PUSH SOUTH. FREEZING
TEMPERATURES ACROSS THE NORTH ARE LOOKING MORE PROBABLE TUESDAY
AND WEDNESDAY MORNING. SOUTHERN LOCATIONS COULD SEE A LIGHT FREEZE
IF CLOUDS CLEAR. GOING FORECAST DOES NOT INDICATED THIS AT THIS
TIME. DAYTIME HIGHS TO REMAIN AS MUCH AS 20 DEGREE BELOW NORMAL
WITH NORTH WINDS CONTINUING THROUGH AT LEAST THE MIDDLE OF NEXT
WEEK.

MARINE...NOW THROUGH THURSDAY...CURRENTLY BUOY020 REPORTS A SOUTH
WIND AROUND 17 KNOTS WITH SEAS AROUND 3.6 FEET. WARMER DEW POINT
TEMPERATURES MOVING OVER COOLER NEARSHORE WATERS HAS RESULTED IN
AREAS OF DENSE SEA FOG IMPACTING PORTIONS OF THE LOWER TEXAS
COASTAL WATERS THIS MORNING. SATELLITE IMAGES ALONG WITH SURFACE
OBSERVATIONS AND WEBCAMS ALONG SOUTH PADRE ISLAND SUGGESTS THAT
THE SEA FOG IS DENSE IN SOME AREAS. A DENSE FOG ADVISORY REMAINS
IN EFFECT UNTIL 8 AM FOR THE LAGUNA MADRE AND THE GULF WATERS OUT
20 NM EAST OF PADRE ISLAND.

HIGH PRESSURE OVER THE GULF OF MEXICO WILL INTERACT WITH LOW
PRESSURE OVER THE CENTRAL PLAINS STATES TO PRODUCE MODERATE WINDS
AND SEAS FOR THE LOWER TEXAS COASTAL WATERS THROUGH THE PERIOD.
SMALL CRAFT EXERCISE CAUTION CONDITIONS WILL BE POSSIBLE AT TIMES
ESPECIALLY FROM 20 TO 60 NM EAST OF PADRE ISLAND.

THURSDAY NIGHT THROUGH SUNDAY...VERY STRONG COLD FRONT EXPECTED
FRIDAY MORNING WITH ANOTHER STRONG NORTH SURGE MONDAY. MARINE
CONDITIONS TO RAPIDLY DETERIORATE FRIDAY WITH WIND GUSTS
APPROACHING GALE FORCE. HAZARDOUS CONDITIONS TO PERSIST THROUGH
THE WEEKEND AND MUCH OF NEXT WEEK.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR GMZ130-132-
     135-150-155.

&&

$$

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HTTP://WEATHER.GOV/RGV

54/58/VEGA